a. ( x-7) + 11 = 3 b. ( x+8) . ( x2 -16) =0 x2 là x mũ 2 c. 4.( x-6) -5.( x-2)= -7

0 bình luận về “a. ( x-7) + 11 = 3 b. ( x+8) . ( x2 -16) =0 x2 là x mũ 2 c. 4.( x-6) -5.( x-2)= -7”

1. @isa

   `a. ( x-7) + 11 = 3`

   `⇔ x – 7 = 3 – 11`

   `⇔ x – 7 = – 8`

   `⇔ x  = -8 + 7`

   `⇔ x = -1`

   Vậy `x = -1`

   `b. ( x+8) . ( x² -16) =0`

   `⇔ (x + 8) . (x – 4). (x + 4) = 0`

   `⇔` \(\left[ \begin{array}{l}x + 8=0\\x-4=0\\x +4=0\end{array} \right.\) 

   `⇔` \(\left[ \begin{array}{l}x=-8\\x=4\\x=-4\end{array} \right.\) 

   Vậy `x ∈ { -8 ; 4 ; -4}`

   `c, 4.( x-6) -5.( x-2)= -7`

   `⇔ 4x – 24 – 5x + 10 = -7`

   `⇔ -x -14 = -7`

   `⇔ -x = 7`

   `x = -7`

    Vậy `x = -7`

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2. $(x-7)+11=3$

   $⇒x-7+11=3$

   $⇒x=-1$

   b, $(x+8)(x²-16)=0$

   $⇒(x+8)(x-4)(x+4)=0$

   ⇒\(\left[ \begin{array}{l}x+8=0\\x+4=0\\x-4=0\end{array} \right.\) 

   ⇒\(\left[ \begin{array}{l}x=-8\\x=-4\\x=4\end{array} \right.\) 

   c, $4(x-6)-5(x-2)=-7$

   $⇒4x-24-5x+10=-7$

   $⇒-x=7$

   $⇒x=-7$

    

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